Field of the Invention
The invention relates to a method for detecting the surface structure and composition of a sample and a device for detecting the surface structure and composition of a sample.
The method according to the invention and the device for detecting the surface structure and composition of a sample by means of a scanning unit can advantageously be used for detecting traces, which are induced by contact of the skin of the human body on the surface of the object or are absorbed by means of a trace carrier, in medical technology for incident light observation during skin cancer examinations, and in the industrial field for detecting surface coatings and for thickness measurement of internal layers of an object.
Description Of Related Art
A device for detecting an imprint on a trace carrier is known from DE 10 2011 111168 A1, which contains a trace carrier support, a receptacle head having a camera, which records infrared beams, and a mount for the receptacle head, using which the receptacle head is mounted in relation to the trace carrier holder. The infrared camera records the infrared beams which are emitted and/or reflected from an imprint on the trace carrier. The receptacle head is arranged in a mount, which contains a telescoping column for setting the distance of the receptacle head from the trace carrier, which can be linearly moved horizontally along a bar held by two bars. The receptacle head additionally has a digital camera for preparing images of an evidence object deposited on the trace carrier and an infrared emitter, which can be moved in a circle about the infrared camera.
The restriction of the scanning surface of the trace carrier to the dimensions of the bar arrangement for moving the receptacle head and the risk of distortions and shading during the scanning of an imprint on the trace carrier and corruption of the scanned images as a result of external light incident on the imprint are disadvantageous in this case.
A method for detecting a fingerprint is known from DE 100 22 143 A1, in which an image of the fingerprint arranged on a trace carrier is recorded in the invisible, infrared wavelength range by means of a camera, so that the image results, not only as in the visible wavelength range due to the reflection or absorption of the incident light, but rather also due to the emitted thermal radiation. For this purpose, the trace carrier is placed on a temperature-regulated supporting surface and irradiated by a light source, which is arranged laterally and offset in height in relation to the temperature-regulated supporting surface. The image is recorded by means of a camera, which is arranged above the trace carrier located on the temperature-regulated supporting surface. The trace carrier is illuminated using light of the desired wavelength range by way of the arrangement of spectral filters on the light source and the camera.
This arrangement for detecting an imprint on a trace carrier has the disadvantage that due to the arrangement of the light source, shading occurs on the structured surface of the imprint as well as nonvisible regions due to the position and the conical field of vision of the camera, which make it necessary to record the imprint at various viewing angles, to be able to calculate a complete three-dimensional image from individual partial images.